Removable external storage media for computers have existed for many years. In fact, punched paper cards developed by Jacquard for controlling looms predate the modern stored program computer. These punched cards have reappeared as removable storage of both programs and data for early generations of large and mid-sized computers. Similarly, punched paper tape provided a means for storing information for both mechanical devices such as teletypewriters and for digital stored program computers.
As storage substrate technology improved, the cost of storage decreased while, simultaneously, the portability of storage increased. These trends are evident in the development of removable magnetic storage. Initially, mainframe removable packs of rigid magnetic disks ("disk packs") were used for fast random access. Although disk packs are comparatively bulky; they are nonetheless portable from mainframe to mainframe. As smaller computers developed, more portable random access mechanisms for storing small amounts of data were developed. The eight inch "floppy disk" allowed a modicum of information to be stored, retrieved, and cataloged off-line. These first floppies were more convenient than either magnetic tape or disk packs and were much less expensive.
Five-and-a-half inch floppy "diskettes" followed, and were dominant for a number of years. These floppy disks are more convenient for handling and storing than their eight inch predecessor. Additionally, these floppies stored more information due to advances in substrate material, recording/playback technology, and processing technology.
Recently, a three-and-a-quarter inch "diskette" format has gained commercial success. No longer "floppy", these diskettes are encased in a semirigid plastic protective shell, providing a more foolproof product for a wider market. Furthermore, the size and protection allow for mailing in standard envelopes, or carrying in standard shirt pockets--something not possible with previous floppy disks.
While this improvement has taken place within the magnetic storage technology, advances in other technologies have also occurred. For example, CD-ROM has grown out of the compact disk digital audio market in the past ten years.
The cost of these media has dropped while their storage capacity has increased since their introduction. A typical three-and-a-quarter inch diskette now holds approximately one megabyte of data and costs about one dollar. A CD-ROM disk presently stores about six hundred megabytes of data and costs about ten dollars.
Central to the operation of all removable media, regardless of storage technology, is the concept of a "file". The concept itself was originally based on the metaphor of a paper file in a filing cabinet. Not until the advent of addressable read/write devices such as magnetic tapes did the concept of a "file" fully develop. Files are ordered collections of digitally encoded data that have an abstract existence independent of their storage medium. Thus, a file can be copied from one storage medium to another and retain its identity. For example, a file might be stored in core memory and copied to a magnetic tape. That magnetic tape, in turn, may be used to download the file into another computer's memory.
Experience with floppy disks and other portable media has shown that the concept of the file is valuable. Its use in over a hundred million of personal computers worldwide has familiarized the public with the concept, and is incorporated into the public consciousness as a basic unit of storage, retrieval, and transportation in the computer world. Files can be stored on floppy disks, tape, or other media and transported to other machines or stored away physically. All of these media are relatively inexpensive and are suited to storage and transportation of large amounts of data.
None, however, is ideally suited to the storage of small amounts of data at a very low price. A typical business letter contains on the order of a thousand bytes of information. Storing the contents of this letter digitally on a floppy disk would cost ten times the amount of the human readable letter paper version, and would waste 99.9% of the storage capacity of the diskette medium.
The primary means of very inexpensive storage for data has, for hundreds of years, been paper. Although the demise of paper has been predicted since the advent of computers, the promise of the "paperless" office has not yet come to pass. In fact, paper carries some important advantages as a medium that make its demise unlikely. For example, paper as a medium is ubiquitous. Paper users are generally more concerned with the stored message than with the substrate medium. By contrast, computer users must still "know" something about the operating system and application programs (e.g. a word processing program) in order to create or read a document.
The format of paper as a medium is standardized. This standardization is of particular benefit to users of documents, since it means low cost access to convenient devices for storing (e.g. :file cabinets, drawers, manila folders, etc.), transporting (e.g. envelopes, facsimile machines) and reproducing (e.g. photocopiers) information. The form factor of paper and its read/write interface have remained stable for nearly a century. By contrast, changes in materials, fabrication, and data recording technology rapidly obsolete magnetic and optical storage media. In these respects, paper has served as nearly ideal for information storage.
In particular, data stored on standardized paper stock (such as letter size, legal size, European or Japanese A4, etc.) can take advantage of the existing paper infrastructure of copiers, file cabinets, envelopes, etc. in order to integrate more fully into existing work practices.
However, until recently, paper has been limited to a human readable storage medium. Recent advances in optical and computer technology have made it possible to use paper as a medium for machine readable information.
Cost reductions and speed increases in digital computer processing units, memories and image scanning devices have made machine readable data storage on paper economically feasible.
Furthermore, paper document handling technology for paper in standard sizes is well understood and highly developed in computers, facsimile machines, and the like. Digital scanners and digital copiers are joining digital facsimile machines in the array of digital electronic paper handling office equipment. With the advent of these digital machines, paper now serves as a means for storing both human readable and machine readable information.
Early methods of storing data on paper, for example bar codes were very low in density and suitable only for identification rather than storage. Higher density encodings, such as Cauzin strip, used rather unsightly formats for the encoding of data. Recently, a more esthetically pleasing method ("glyph" codes) for encoding data on paper has emerged. This "glyph" method for encoding high densities of data on paper in an attractive form is described in pending U.S. patent application Ser. No. 07/887,563 by Zdybel, filed on May 18, 1992, a continuation in part of Ser. No. 07/530,677 which was filed on May 30, 1990 and is now abandoned, and is assigned to Xerox Corporation. Zdybel et al. is hereby incorporated by reference into the present application.
Returning to the typical business letter example, a digitally encoded version of the contents of the letter could be stored on a single sheet of paper, which could be printed at a cost of about five cents. Such digitally encoded files can be copied using conventional light-lens copiers, or future generation digital copiers. They can be mailed in an envelope, or transmitted in a facsimile machine. They can also be stored in a filing cabinet, or scanned in through a copier or digital scanner to produce a digitally encoded file, abstracted from its medium of encoding.
While a thousand business letters could be stored more economically and more compactly on a floppy disk, a small number of files containing a few business letters are more economically and more conveniently stored on paper using the above mentioned glyph code technology.
It is therefore an object of the present invention to combine the use of paper as a substrate for storing machine readable information, the use of preexisting standardized paper sizes to facilitate integration and the use of the file as a conceptual unit for bundling information to provide a convenient, easily accepted, easily used means of inexpensively storing moderate amounts of data in a typical office or home environment.